The present invention relates to the field of microparticles intended to be administered by injection or by the subcutaneous or muscular route.
There is currently a need for prolonged-release pharmaceutical formulations intended for the administration of proteins by injection, which are free of any trace of organic solvents.
Intense efforts have to be made to develop efficient novel systems for the administration of proteins. All the conventional techniques for preparing controlled release injectable microparticulate systems, whether they be the preparation of microcapsules by the emulsion (oil/water)/solvent evaporation method (Hora et al., Pharm. Res., 7 (1990), 1190-1194; Jalil, R. et al., L. Microencapsulation, 7 (1990) 294-325), the coacervation method in organic phase (Ruiz et al., Pharm. Res., 7 (1990) 928-934; McGee, J. P. et al., J. Controlled Release, 34 (1995) 77-86) or by the double emulsion (water/oil/water)/solvent evaporation technique (Ogawa, Y et al., Chem. Pharm. Bull., 36 (1988) 1095-1103), lead to the use of organic solvents. These require steps for accurately controlling and measuring the levels of residual solvents in order to limit these levels and to avoid any harmful side effects on the patient. Furthermore, government authorities introduce strict standards for avoiding contamination of the environment with the organic solvents inherent to the methods of production and to limit or even eliminate the use of organic solvents in pharmaceutical compositions. Finally, in protein formulations, problems of denaturation induced by contact with solvents and undesirable phenomena of adsorption at solvents/water interfaces can occur.